settings: Add flex/bison based parser for strongswan.conf

This parser features several improvements over the existing one. For instance, quoted strings (with escape sequences), unlimited includes, relaxed newline handling (e.g. at the end of files or before/after { and }), and the difference between empty and unset values (key = vs. key = ""). It also complains a lot more about invalid syntax. The current one accepts pretty odd stuff (like settings or sections without name) without any errors or warnings.
2014-05-15 11:28:06 +02:00
parent f99d1f7ba5
commit 1f669078ac
5 changed files with 501 additions and 1 deletions
@@ -0,0 +1,193 @@
+%{
+/*
+ * Copyright (C) 2014 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "settings_parser.h"
+
+#include <utils/parser_helper.h>
+
+bool settings_parser_open_next_file(parser_helper_t *ctx);
+
+static void include_files(parser_helper_t *ctx);
+
+%}
+%option debug
+%option perf-report
+
+%option warn
+
+/* use start conditions stack */
+%option stack
+
+/* do not declare unneded functions */
+%option noinput noyywrap
+
+/* don't use global variables, and interact properly with bison */
+%option reentrant bison-bridge
+
+/* maintain the line number */
+%option yylineno
+
+/* don't generate a default rule */
+%option nodefault
+
+/* prefix function/variable declarations */
+%option prefix="settings_parser_"
+/* don't change the name of the output file otherwise autotools has issues */
+%option outfile="lex.yy.c"
+
+/* type of our extra data */
+%option extra-type="parser_helper_t*"
+
+/* state used to scan include file patterns */
+%x inc
+/* state used to scan quoted strings */
+%x str
+
+%%
+
+[\t ]*#[^\n]*			/* eat comments */
+[\t ]+					/* eat whitespace */
+\n|#.*\n				return NEWLINE; /* also eats comments at the end of a line */
+
+"{"						|
+"}"						|
+"="						return yytext[0];
+
+"include"[\t ]+/[^=]	{
+	yyextra->string_init(yyextra);
+	yy_push_state(inc, yyscanner);
+}
+
+"\""					{
+	yyextra->string_init(yyextra);
+	yy_push_state(str, yyscanner);
+}
+
+[^#{}="\n\t ]+			{
+	yylval->s = strdup(yytext);
+	return NAME;
+}
+
+<inc>{
+	/* we allow all characters except #, } and spaces, they can be escaped */
+	<<EOF>>				|
+	\n|#.*\n			|
+	[\t ]				{
+		if (*yytext && yytext[strlen(yytext) - 1] == '\n')
+		{	/* put the newline back to fix the line numbers */
+			unput('\n');
+			yy_set_bol(0);
+		}
+		include_files(yyextra);
+		yy_pop_state(yyscanner);
+	}
+	"\""				{	/* string include */
+		yy_push_state(str, yyscanner);
+	}
+	\\					{
+		yyextra->string_add(yyextra, yytext);
+	}
+	\\["#} ]			{
+		yyextra->string_add(yyextra, yytext+1);
+	}
+	[^"\\#}\n\t ]+ {
+		yyextra->string_add(yyextra, yytext);
+	}
+}
+
+<str>{
+	"\""				|
+	<<EOF>>				|
+	\n					|
+	\\					{
+		if (!streq(yytext, "\""))
+		{
+			if (streq(yytext, "\n"))
+			{	/* put the newline back to fix the line numbers */
+				unput('\n');
+				yy_set_bol(0);
+			}
+			PARSER_DBG1(yyextra, "unterminated string detected");
+		}
+		if (yy_top_state(yyscanner) == inc)
+		{	/* string include */
+			include_files(yyextra);
+			yy_pop_state(yyscanner);
+			yy_pop_state(yyscanner);
+		}
+		else
+		{
+			yy_pop_state(yyscanner);
+			yylval->s = yyextra->string_get(yyextra);
+			return STRING;
+		}
+	}
+	\\n     yyextra->string_add(yyextra, "\n");
+	\\r     yyextra->string_add(yyextra, "\r");
+	\\t     yyextra->string_add(yyextra, "\t");
+	\\b     yyextra->string_add(yyextra, "\b");
+	\\f     yyextra->string_add(yyextra, "\f");
+	\\(.|\n)			{
+		yyextra->string_add(yyextra, yytext+1);
+	}
+	[^\\\n"]+			{
+		yyextra->string_add(yyextra, yytext);
+	}
+}
+
+<<EOF>>					{
+	settings_parser_pop_buffer_state(yyscanner);
+	if (!settings_parser_open_next_file(yyextra) && !YY_CURRENT_BUFFER)
+	{
+		yyterminate();
+	}
+}
+
+%%
+
+/**
+ * Open the next file, if any is queued and readable, otherwise returns FALSE.
+ */
+bool settings_parser_open_next_file(parser_helper_t *ctx)
+{
+	parser_helper_file_t *file;
+
+	file = ctx->file_next(ctx);
+	if (!file)
+	{
+		return FALSE;
+	}
+
+	settings_parser_set_in(file->file, ctx->scanner);
+	settings_parser_push_buffer_state(
+			settings_parser__create_buffer(file->file, YY_BUF_SIZE,
+										   ctx->scanner), ctx->scanner);
+	return TRUE;
+}
+
+/**
+ * Assumes that the file pattern to include is currently stored as string on
+ * the helper object.
+ */
+static void include_files(parser_helper_t *ctx)
+{
+	char *pattern = ctx->string_get(ctx);
+
+	ctx->file_include(ctx, pattern);
+	free(pattern);
+
+	settings_parser_open_next_file(ctx);
+}